1. Field of the Invention
The present invention deals with novel emulsifiers that have excellent feel on the skin are essentially non-irritating to the eyes and skin and can be used to make unique silicone in water and water in silicone emulsions. The compounds are esters made by the reaction of sorbitol and carboxy functionalized silicone compounds. The introduction of the silicone portion of the molecule into the compounds of the present invention results in improved emulsification efficiency of silicone oils, improved oxidative stability and improved liquidity of the sorbitan esters as well as an outstanding skin feel of emulsions made with said emulsifiers. Emulsions made with standard sorbitan esters have a tendency to be sticky and cosmetically unappealing.
2. Description of the Art Practices
U.S. Pat. No. 5,296,625 to O'Lenick et al discloses silicone alkoxylated ester carboxylates. These carboxylates are not suitable to make sorbitan esters, since the linkage group from silicone to the carboxyl group is through an ester group. This group will hydrolyze in the presence of acid or base, and will transesterify if the attempt to react it with sorbitol is made.
Sorbitan esters have likewise been known for years. U.S. Pat. No. 2,322,821 describes the chemistry.
U.S. Pat. No. 6,013,813 issued Jan. 11, 2000 discloses guerbet based sorbitan esters. The guerbet gives improved oxidative stability over standard sorbitan esters, but does not address skin feel and the ability to provide very efficient emulsifiers for silicone oil.
U.S. Pat. No. 5,292,847 incorporated herein by reference issued in March 1994 discloses carboxy silicone alkoxylates. These carboxy silicones are raw materials in the preparation of the compounds of the present invention.